The Melted Coins is the twenty-third volume in the original The Hardy Boys series of mystery books for children and teens published by Grosset & Dunlap.

This book was written for the Stratemeyer Syndicate by Leslie McFarlane in 1944. Between 1959 and 1973 the first 38 volumes of this series were systematically revised as part of a project directed by Harriet Adams, Edward Stratemeyer's daughter. The original version of this book was rewritten in 1970 by Andrew E. Svenson